Discharge tube spacer



Se t. 26, 1944. A. c. ROCKWOOD DISCHARGE TUBE SPACER Original Filed Aug. 17, 1940 Fla. 1.

hwEN-ro ALAN G. RocKwooD,

Patented Sept. 26, 1944 UNITED STATES PATENT OFFICE 2,858,829 DISCHARGE TUBE SPACE-R Alan C. Rockwood, Newton, Mass., ass'ignor, by

mesne assignments, to Raytheon Manufacturing Company, Newton, Mass, a corporation of Delaware 3 Claims. (Cl. 250-275) This is a division of applicant's copending application, Serial No. 353,108, filed August 1'7, 1940, now Patent No. 2,266,080, issued December 16, 1941.

This invention relates to an electrical space discharge .tube of the vacuum type in which the dimensions of the tube are reduced to relatively small value. In such a tube the problem of mounting the various tube elements on the usual insulating spacer presents various difilculties because of the small space available.

An object of this invention is to devise a novel insulating spacer with which the tube elements may be readily assembled.

Another object is to simplify the assembly and manufacture of tubes of small size.

The foregoing and other objects will be best understood from the following description of an exempliflcation thereof, reference being had to the accompanying drawing, wherein:

Fig. 1 is a cross-section of my novel tube taken along line l--i of Fig. 3;

Fig. 2 is a right-hand view of the electrode assembly shown in Fig. 1 with the glass envelope shown in cross-section;

Fig. 3 is a top view of the electrode assembly of Fig. 1: and

Fig. 4 is an enlarged portion of one of the insulating spacers showing a detail thereof.

The tube illustrated contains an electrode assembly consisting of an anode i, a filamentary cathode 2, and a plurality of grids 3, 4 and 5. The grids are wound upon and supported by grid side rods 8-6, l--! and 8-8, respectively. Proper spacing and support of the electrodes are provided by upper and lower insulating spacers 9 -9, preferably of mica. The spacers 9-9 are cut away to provide resilient projections l which are adapted to resiliently engage the inner walls of the glass envelope. The spacers 9 are each provided with a triangular slot ll having a rectangular recess l2 in the base thereof in order to receive and support one of the side rods 8 of the grid 3.

The filamentary cathode 2 is retained in the apex of each of the triangular slots ll. ,In-order to support the lower end of the filamentary cathode 2, a, U-bracket I3 is secured to the lower spacer 9 and projects from the lower side thereof. The bracket is has welded thereto a tab H which in turn is welded to the lower end of the filamentary cathode 2, and serves as a mechanical support and electrical connector therefor. A conducting spring member i is welded at one end to the upper end of the filamentary cathbde 2, and at its other end to one of the side rods 8 of the grid I. The Spring pulls upwardly on the filamentary cathode 2, and maintains the proper tension thereon. Furthermore, said spring projects beyond the apex of the upper triangular slot I I so as to force the upper end of the filamentary cathode into the apex of said triangular slot. Likewise the tab i4 is located beyond the apex of the lower triangular slot ii so as to maintain the lower end of the filamentary cathode in said apex.

The anode I is provided with a plurality of tabs l6 at its upper edge and a plurality of tabs I1 at its lower edge. These tabs are bent over onto the upper and lower surfaces of the upper and lower spacers 9, respectively, and serve to maintainthe electrode assembly in its assembled form, whereby it may be readily handled as a unit before insertion into the glass envelope. As an additional means for retaining the grid 5 in place within the electrode assembly, one of the side rods 8 may be provided with stops l8-l8 welded to the upper and lower ends of said side rod and bearing against the upper and lower faces of the upper and lower spacers 9, respectively.

In order to provide for an external electrical connection to the anode I a connector [9 is welded to one of the lower tabs I1 and also to a lead-in conductor 20. Lead-in conductors 2!, 22, 23 and 24 are also provided for the electrodes 2, 8, 4 and 5, respectively. For this purpose the lead-yin 2i is welded to the bracket IS, the leadin '22 is welded to one of the side rods 6, the lead-in 23 is welded to one of the side rods 1, and the lead-in 24 is welded to one of the side rods 8. A ring 25 of getter material may be conveniently supported on the electrode assembly by being welded to the upper end of one of the side rods 8.

The triangular slot and rectangular recess l2 in the upper and lower insulating spacers greatly facilitate the assembly of the tube structure, particularly in the small dimensions available. For example, the tab I of the filament 2 can readily be threaded through the combined opening, whereas if the triangular slot l I alone were available, such threading would be relatively dimcult. Also due to the combined arrangement of the openings H and I2, the side rod 6 of the grid 3 can readily be assembled therein despite the close spacing. Also the combined opening is easier to fabricate in insulating spacers of the comparatively small area which must be used in tubes of this kind.

In order to eliminate vibration of the filament, a spring wire 26 is provided. One end of this spring wire is welded to a tongue 21 formed in the side wall of the anode l by cutting a U-shaped slot therein. The spring wire 26, except for the point at which it is welded to the tongue 21, is covered with an insulating coating 28 bearing against the filament 2. Any tendency for vibration to occur is absorbed by the spring wire 26 and the insulating coating 28 thereon.

The above electrode assembly is inserted as a unit within a straight-sided glass tube 29. The lower end of this tube is heated and softened sufflciently so that it may be pressed to make the press or seal 30. The upper end of the tube 29 is provided with the usual tubulation, exhausted and sealed oil at 8|.

course it is to be understood that this invention is not limited to the particular details as described above as many equivalents will suggest themselves to those skilled in the art. For example, the invention can be applied to tubes of other types in which other numbers of grids might be used. Various other changes embodying the teachings of this invention will suggest themselves to those skilled in the art. It is accordingly desired that the appended claims be given a broad interpretation commensurate with the scope of the invention within the art.

What is claimed is:

l. A unitary electrode assembly for an electrical space discharge tube comprising a filamentary electrode, an additional electrode, upper spacers, a bracket secured to the outer side of one of said spacers, an angular slot in each of said spacers, a resilient tension member secured to said assembly adjacent the outside of the other of said spacers, said filamentary electrode being supported between said bracket and said tension member in engagement with an apex of each of said slots.

3. A unitary electrode assembly for an electrical space discharge tube comprising a filamentary electrode, an additional electrode, insulating spacers comprising solely upper and lower insulating spacers, a bracket secured to the outerside of one of said spacers, a V slot in each of said spacers, and a resilient tension member secured to said assembly adjacent the outside of the other of said spacers, said filamentary electrode being supported between said bracket and said tension member in engagemnet with the apex of each of said slots.

ALAN C. ROCKWOOD.

- CERTIFICATE OF CORRECTION. Patent No. 2, 8,829. 7 September 26, 19M.

ALAN c. RocKwooD. Y

It is hereby certified that error appears in the printed specification of the above numbered patent requiringcorrection as follows: Page 2, seco d column, line 1, for U-spaced" read II-shaped"; line 11, for the word 'spaces read --spacers-"-; line 31, for "engagemnet" read -engagement---; and that'the said Letters Patent shouldbe read with this correction therein that the same may conform to the record of the case in the Patent'Office Signed end sealed this 28th day of November, A. 1). 191m.

Leslie Frazer (Sea1)' Acting Commissioner-of Patents. 

